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Biology: course work
Question 1
Clostridia are saprophytic pathogens that are disease causing to humans and occur in
many strains. Clostridium difficile is the causative for nosocomial diarrhea and exists as two
toxins: A which is an enterotoxin and B a cytotoxin. Since spores are the means of transmission
to distinguish if patients got it from the hospital or the community both areas should be checked
for spore presence which should then be cultured then compared. To distinguish if patients have
similar strains those with strain A, show effects in the epithelium of the ileum while those with
strain B will occur in all cells. (Glyles, Presscott and Songer, 472-475).
Tdc is a blend of esterified fatty acids that help in inhibiting of Bacteria. All Clostridial
genes are encoded by a protein that is 14.5 kDa which is TcbC and based on its amino acid
sequence could be similar or dissimilar. Tdc A, B and C are genes that encode regulatory
proteins such as enzymes and are activated by Clostridial TbcC and occur due to mutation. TdcB
is expressed in the Lac operon and in the genes of chromosomes. Ribotype 027 is a type of toxin
found in found in hospitals during PCR and causes Clostridium difficile Associated Disease
(CDAD). Mutation of this strain during PCR increases its virulence and makes it resistant to
many antibiotics such as ciproflaxocin.
Question 2
Staphylococcus aureus produces an enterotoxin responsible for diarrhea and vomiting
(Holmeberg and Blake, 487-489). Persons taking antibiotic against a strain of this bacterium yet
exposed to it via contaminated food will still get similar symptoms thus the antibiotic will be
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ineffective. The presence of skin lesions and food poisoning do not correlate with food poisoning
since when food is contaminated the multiplication rate is very high and is accelerated by rapid
cooling, not cooking and refrigeration. This syndrome is determined by enterotoxin B, targets the
small intestine, GIT and blood and may cause hypertension and fatalities in infants while isolates
from scalded skin is caused by pyrogenic toxins of the Bacteria, affects the skin cells and is not
fatal (Ulrich, Sidel and Taylor, 627). The more the cells of the Bacteria the more virulence it will
be, 87 people have been hospitalized due to eating pastries but mostly children since they are
more vulnerable. Further the presence of many cells, the faster they spread and the more people
they reach. Contrary to Pro Med posting on eclairs the expression of the toxin would be high
since they are eaten by many and their preparation involves fluctuations in temperature then
storage allowing bacteria growth (Ulrich, Sidel and Taylor, 627).
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Work Cited
Gyles, Carlton. , Presscott, John and Songer, Glenn. “Journal of clinical microbiology”
Clostridium difficile. Issue 18(2005): American Society of microbiology.
Holmberg and Blake.“Staphylococcal food poisoning in the United States” New facts and old
misconceptions. (1984) JAMA.
Ulrich, Sidell and Taylor. “Staphylococcal enterotoxin B and related pyrogenic toxins in
Medical Aspects of Chemical and Biological Warfare”, Borden Institute, Washington, DC.